The aim of the study is to gather safety information from the three year, long-term use of entacapone and to give the patients an opportunity to use entacapone after paticipating in the controlled, double-blind, study 2939044. In 1997, the study was extended until 12/31/99 or until entacapone is commercially available. Recruitment for this study is completed. The controlled trial demonstrated that entacapone was effective at increasing the duration of response to levodopa and at relieving parkinsonism in patients experiencing motor fluctuations during the 24 weeks of treatment. Signs and symptoms of Parkinson's disease are sometimes incompletely treated by current antiparkinsonian drugs. The original study was an investigator initiated (Parkinson Study Group) 32 week placebo-controlled, double-blind, randomized, parallel group design and evaluated 200 individuals with idiopathic PD at 18 centers in North America. At the MGH, 12 PD subjects from our Movement Disorder Unit who had motor fluctuations were recruited. This industry initiated follow-on study will be an uncontrolled, open-label study for all patients who have completed the controlled study. Duration of the study will be up to three years; the patient must attend all scheduled follow-up visits in order to receive enacapone treatments. Primary variables will be safety (laboratory parameters, vital signs, and adverse event monitoring which will include the monitoring of drug interactions). Secondary variables during year one only will be to assess the clinical effects (UPDRS standardized rating scale and global evaluation). Study treatment will be 200mg of entacapone tablets in combination with ech scheduled levodopa (Sinemet) dose to a maximum of 10 doses per day. There will be no planned remuneration.